Britain celebrates birth of a princess

Prince William's wife Kate gave birth to a baby girl on Saturday to cheers from a crowd of well-wishers outside the hospital as Britain celebrated the royal family's new fourth in line to the throne.

The birth was announced to the world in a tweet from Kensington Palace, the couple's London residence, and by a traditional town-crier in a feathered tricorne hat ringing a bell on the steps of the clinic.

A proclamation signed by the royal doctors was also placed on a gilded easel in front of Buckingham Palace, where hundreds of onlookers crowded by the gates to witness the historic moment.

"Her Royal Highness The Duchess of Cambridge was safely delivered of a daughter at 8.34am," the Kensington Palace press office said in a statement.

Mother and baby "are both doing well," it said.

William was present for the birth and the princess weighed eight pounds and three ounces (3.7 kilos).

A smiling William said he was "very happy" as he later emerged from the Lindo Wing of St Mary's Hospital to be with their son Prince George in Kensington Palace.

Great-grandmother Queen Elizabeth II and other senior members of the royal family were informed before the formal announcement and grandfather Prince Charles was said to be "absolutely delighted" at the news.

The queen wore a pink dress and shawl at a military parade she attended in northern England later on Saturday in apparent homage to the latest arrival.

"I'm absolutely delighted," Prime Minister David Cameron said, leading congratulations from around the country that included the message "It's a Girl" scrolled on a display on top of London's BT Tower.

Royal navy sailors on board HMS Lancaster sent a unique message of congratulations by lining up on the flight deck to spell out the word "sister".

In Australia, which William and Kate visited last year, Prime Minister Tony Abbott sent a message saying his country "shares this young family's joy".

- 'It's a girl!' -

Media teams from around the world rushed to the private maternity wing of St Mary's hospital in the early morning, joining a group of royal superfans who have remained camped outside for more than a week.

The baby was born less than three hours after Kate was admitted to hospital at around 6.00 am, compared to the more than 10 hours of labour with George.

"It's a girl! It's a girl!" the diehard supporters sang out after the birth was announced, also intoning the tune of "Happy Birthday" for the royal baby.

The new Princess of Cambridge will be fourth in line to the throne after Queen Elizabeth's eldest son Charles, grandson William and great-grandson George.

She is the first major royal who cannot be overtaken in the line of succession by any future younger brothers following changes to the monarchy's rules.

The name favoured by bookmakers is Alice, followed by Charlotte. The last royals named Alice include Queen Victoria's daughter, Princess Alice of Hesse, and Prince Philip's mother, Princess Alice of Battenberg.

Many supporters spoke of their memories of William's late mother, Princess Diana, who gave birth to William and his brother Harry in the same clinic.

She died in a car crash in Paris in 1997 and her memory is still cherished by many Britons.

At Buckingham Palace, a queue formed to file past the easel announcing the royal birth.

"It's an unforgettable day in my life," said Joy Buttinger, a nurse living in Austria who was on holiday with her 18-year-old daughter.

William and Kate are planning to spend the first few days after the birth at Kensington Palace.

They will then travel to Anmer Hall, a secluded 10-bedroom country mansion on Queen Elizabeth's privately-owned Sandringham estate in Norfolk, eastern England, where they have set up home.

Cannons will be fired on Monday to celebrate -- 62 from the Tower of London and 41 from Green Park.

There will alo be a military parade past Buckingham Palace with soldiers, horses and guns from The King's Troop Royal Horse Artillery regiment.

The 500-year-old Royal Mail will commemorate with a special message to appear on millions of letters and parcels delivered nationwide on Tuesday.

The postmark reads "Congratulations TRH The Duke and Duchess of Cambridge on the birth of their daughter" and it is the first time in the company's history that a royal birth has been commemorated in this way.